Small businesses, home offices, and enterprises interested in reducing overhead costs use shared telephone lines. Many business enterprises use shared communication (e.g., telephone) lines in their private branch exchange (PBX) system to allow more than one person to answer a call and to achieve cost savings. In a shared telephone line system, an incoming call to a single telephone number or extension is directed to a plurality of telephone devices, with each device usually being associated with a different person or work environment. In many cases, a receptionist or Interactive Voice Response (IVR) unit answers the calls and then directs each call to an extension or line that is shared by multiple persons. For example, a manager may share a line with his assistant or secretary such that an incoming call to the number or extension rings on both of their telephones. In other cases, a user may apply a shared line to multiple phones intended to reach that individual, such as where an incoming call simultaneously rings to a person's desk phone and their laboratory phone.
Numerous systems and methods exist for handling telephone calls in a shared line environment. For example, U.S. Pat. No. 6,870,835 teaches a method of handling incoming calls directed to a virtual communication subscriber who is connected to a communication network via a shared line system. U.S. Pat. No. 5,432,844 teaches an automated telephone line sharing and lockout apparatus that allows only one telephone set or other communication apparatus to be connected to a shared line. A shared telephone line answering system in which extension telephone answering devices can be temporarily disarmed so they do not respond to tone codes that might otherwise activate them is disclosed in U.S. Pat. No. 4,805,210.
A number of commercial communication system products are available that combine call processing and IP telephony with many of the functions of a conventional IP-PBX system for business enterprises. For instance, Cisco's CallManager™ is a software-based call processing component that extends enterprise telephony features and functions to packet telephony network devices such as IP phones, media processing devices, voice-over-IP (VoIP) gateways, and multimedia applications. Additional data, voice, and video services such as unified messaging, multimedia conferencing, collaborative contact centers, and interactive multimedia response systems may interact with the IP telephony solution through the CallManager™ open telephony application programming interface (API).
In an existing version of the CallManager™ call processing software, when an incoming call is received at a telephone device (e.g., IP phone) the user can make the call private by pressing a “Privacy” softkey or button on their telephone device. When the Privacy button is pressed (i.e., in an “on” state) call information such as the calling number, the name of caller, etc., that is normally displayed is suppressed for all of the devices on the shared line other than the device answering the call. That is, call information is no longer displayed on the other telephone devices connected to the shared line. Instead, after the call has been answered and the Privacy button pressed, the other devices on the shared line typically display the words “In Use” or “Private”. In addition, pressing the Privacy button prevents others from listening to the call by cutting off the media stream to all of the other devices on the shared line.
One problem with the Privacy button feature on existing call processing systems is that privacy is provided only after the call has been answered. This means that while the call is ringing, the call information is revealed on all of the devices connected to the shared line. In other words, until the time that the call is answered, persons who may be viewing any telephone device on the shared line can see the call information. Even after the call has been answered, until the Privacy button is pressed others may join in the call simply by picking up one of the shared line telephone devices.
What is needed therefore is a call processing system that overcomes the drawbacks of the prior art and which provides enhanced call privacy for both the caller and the called party in a shared line communication system